Condensation of metallic vapors



Feb" 9 1937 G. F. WEATON ET An.

CONDENSATION OF METALLIC VAPORS Filed May 5, 1936 SSN@ Patented Feb'. 9, 1937 UNITED sTATEs 'l PATENT OFFICE Beaver, Pa.,

assignors to St. Joseph Lead Company, New York, N. Y., acorporation'of New York Application May 5, 1936, Serial No., 78,060 In Great Britain February 11,1935

18 Claims.

This invention relates to an improved method and apparatus for the condensation of metallic vapors of the volatile metals,particularly zinc, by passing the metallic vapor into 'an enclosed mass of molten metal wherein it is subject to such conditions that condensation of the vapor therein is practically complete.

The invention makes possible continuous and highly eicient condensation of zinc vapor with avoidance of the production of any material amount of blue powder.

In accordance withthe preferred practice of the invention, the zinc vapor and accompanying gases, from which air is excluded, are conducted from the furnace through an insulated conduit to an insulated entrance chamber, thus maintaining the vapor and gases at a temperature above the condensation point of the vapor. From the entrance chamber, which is contiguousto one end of a receptacle enclosing a mass of molten zinc, the vapor and gases are introduced into said mass at a substantial distance below its upper exposed surface which is at the opposite end of the receptacle.

At the other end of the receptacle is an exit chamber into which the uncondensed gases escape after passing through the mass of molten metal. A suction is applied to draw oif these gases, which is sumciently strong to raise and maintain the level of the upper exposed surface of the molten metal at the necessary substantial height above the level of its lower exposed surface'and to depress and maintain said lower surface at a level that permits the vapor and gases 5 to enter the mass of molten metal just above said lower exposed surface.

The vapor and gases are maintained submerged in said mass by the inclined enclosing roof of said receptacle and travel upwards in'an inthe vapor in the molten metal comes in contact only with such metal and with surfaces actively wiped thereby, the condensation of z inc vapor iS clined path through the circumferentially cona (Cl. 26S- 19) accomplished substantially without the production of blue powder.

The invention, while particularly described with reference to zinc, may be applied to the condensation of other volatile metals such as mercury, cadmium, magnesium and tin.

The invention will be more particularly de-4 scribed with reference to the accompanying drawing showing the preferred form of apparatus in which:

Fig. 1 is a schematic representation, with pori tions broken away, of equipment embodying the invention; and

Fig. 2 is a vertical section on line 2-2 of the condenser illustrated in Fig. l.

The vapors and the gases are conducted from they furnace, not shown, where they are generated, through a heat insulated conduit 2|, into an entrance chamber 2`which is likewise heat insulated.

A condensing receptacle I, which may be of any desired shape, but is preferably tubular and `ovoid in cross-section (as shown in Fig. 2), although not necessarily so, connects the lower end of the entrance chamber 2 with an exit chamber 3. The roof portion of this receptacle is advantageously inclined at an angle of from 45 to 75, preferably from 55 to 65, from the vertical. A pipe leads from the exit chamber to an exhaust pump 4 which pumps the gases, escaping from the exposed upper surface of the liquid mass, from the exit chamber into a gas holder I4. This pump is sufficiently powerful to maintain in the exit chamber a reduction in the gas pressure below atmospheric equivalent to atleast six inches of mercury and thus serves not only to remove by suction the escaping gases, but also to create and maintain the substantial difference in level between the exposed surfaces in said exit and entrance chambers, respectively, as is necessary for successful operation. The elongated or tubular condensing receptacle I is preferably constructed with a metal casing ll'hav ing a refractory lining I8. It is advantageously provided internally with baiiles 5 depending from its roof and with surge baiiles 6 extending across the receptacle. To regulate the temperature of the molten metal, which is raised by the vapor condensation, the exterior of the condensing receptacle I may be cooled by liquid sprayed from the pipe I5 and collected in the trough I5'. The molten metal may be tapped on through any suitable outlet communicating with the molten metal in the condensing chamber, in inlet .chamber 2,

or in outlet chamber 3, but in the apparatus shown we provide an automatic discharge. At or near the connection of the upper end of the receptacle I to the exit chamber 3 is a horizontal outlet having a downwardly depending curtain 'I and a dam 8 that leads to a barometrlc leg 9. This leg leads to a forehearth In for holding the molten metal which mayv be Withdrawn therefrom into molds. Above chamber 3 there may be a gas washer I2 provided with sprays I I draining into sump I3 through pipes I9 and 20.

To initiate the operation, the receptacle I is first provided with a suitable amount of molten metal. Reduced gas pressure in the exit chamber is created and maintained by the exhaust pump. This lifts the upper exposed surface of the molten metal towards or above the upper level Ia and depresses the exposed surface of the liquid at the lower end of the entrance chamber 2 to the level Ib,v so that the level Ib is below the lower end I6 of the inclined roof portion of the receptacle and is a substantial vertical distance below the level Ia. By substantial we mean that this distance is suflicient, under the conditions present, to provide a path for the flow of the vapor in the liquid mass that is long enough to allow time for the condensation in that mass of large volumes of vapor. The vertical height from Ib to Ia is, in the case of the preferred apparatus herein described, when used for the condensation of zinc, at least 12 inches. As the level of the lower exposed surface of the liquid Ib is below the corner I6, the vapor and gases from the furnace ow from the entrance chamber 2 under the corner i6 and into the circumferentially conned mass of molten metal in the receptacle I. Said receptacle, for its length from just beyond the corner I 6 to the upper exposed surface la, is in normal operation lled throughout its transverse cross-section with the mass of molten metal through which the vapor forces its passage until condensed therein.

The inclination of'the roof of the receptacle from the vertical, along and against which roof the vapor and the gases try to flow, retards their flow through the molten metal by providing an inclined path for such flow, which is preferably at least twice as long as theA vertical distance between the corner I6 and the level of the upper exposed surface la of the molten metal. The

f bailles 5 and 6, submerged in the liquid mass in receptacle, serve to retard further that flow and also to agitate the vapor and gases in the molten metal, the bailles 6 being particularly effective in preventing objectionable surging of such metal.

The vapor and gases are thus agitated, broken up and subidvided into bubbles and dispersed through the molten metal and, by providing a sufliciently long path for their travel within the liquid and retarding their ow therein, suicient time is provided for the complete condensation of large volumes of metallic vapor. Io maintain the liquid metal at substantially the desired constant temperature, it is cooled by any suitable means, as, for example, by spraying the outside ofthe condenser receptacle by water sprays I5.- Thus conditions for the most eflicient condensation of the vapor in the liquid mass are realized.

As the volume of liquid metal increases, due to the condensation of the metallic vapor, the surplus may be tapped off.A As shown, such surplus flows over the dam 8 through the barometric leg 9 into the forehearth I0. 'Ihe uncondensed gases drawn from the exit chamber v2 may be collected in gas holder I4 after being washed by the sprays II. The solids may be collected in receptacle I3.

In the process of our invention, above set forth, the zinc vapor has little or no opportunity to form blue powder. Before it enters the mass of molten metal it is maintained at a temperature above that of its condensation. When in said liquid mass the vapor comes in contact only with molten metal and with surfaces of the receptacle vwhich are submerged in and energetically wiped by the agitated molten metal. As these surfaces are the only surfaces with which the vapor cornes in contact, that are below the temperature of its condensation, the formation of blue powder is practically eliminated. If perchance there should be some particles of blue powder in the mass of molten metal, the heat and agitation ofthe molten zinc tend to amalgamate these particles with the molten metal and thus rid the mass of molten metal of them.

This application is a continuation-in-part of applications Serial No. 714,730 and Serial No. 714,731, led March 8, 1934.

We claim:

1. The method of condensing zinc vapor which comprises providing a mass of molten zinc circumferentially confined except at opposite ends thereof, conducting gases and zinc vapor from a furnace to the exposed surface of said mass at one end thereof while maintaining the temperature of said vapor above the condensation point thereof, drawing ofi' the gases from a space above the exposed surface of said mass at the opposite end thereof by suction equal to at least 6 inches of 'mercury, thereby raising the liquid zinc at said latter end and lowering it at the former end so that the level of. the upper exposed surface of the liquid is at least 12 inches higher vertically than the level of the lower exposed surface of the liquid and said lower exposed surface is brought to a level that permits said gases and vapor to ow into said mass of liquid at least 12 inches below its upper exposed surface, conducting said gases and vapor in said mass in an inclined upward direction, impeding the iiow of said gases and vapor in said mass thereby agitating and breaking up the same into bubbles and retarding their flow, contacting said bubbles in said mass only with the molten metal or with surfaces wiped by said metal, retaining said vapor in said mass for suilicient time to condense substantially all of it, delivering the uncondensed gases to the space above the upper exposed surface of said mass, regulating the temperature of said mass of liquid by cooling it, and drawing off the accumulated molten metal.

2. The method of condensing zinc vapor -which comprises providing a mass of molten zinc circumferentially confined except at oppo- `site ends thereof, conducting gases and zinc vapor from a furnace to the exposed surface of said mass at one end thereof, drawing off the gases from a space above the exposed surface of said mass at the opposite end thereof by a suction powerful enough to raise the exposed surface of liquid zinc at one end atleast 12 inches higher vertically than the level of the other exposed surface of the liquid and to depress said lower exposed surface to a level that permits said gases and vapor to iiow into said mass of liquid at least 12 inches below its upper exposed surface, conducting said gases and vapor in said mass in an inclined upward di- 2,010,161 rection, impeding the flow of said gases and.

vapor in said mass thereby agitating and breaking up the same into bubbles and retarding their flow, contacting said bubbles in said mass only with the molten metal or with surfaces wiped by' said metal, retaining said vapor in said mass for suiiicient time to condense substantially all of it, and delivering the uncondensed gases to the space above the upper exposed surface of said mass.

3. The method of condensing zinc vapor which comprises providing a mass of molten zinc circumferentially confined except at opposite ends thereof, conducting gases and zinc vapor from a furnace to the exposed surface of said mass at one end thereof, drawing off the gases from a space'above the exposed surface of said mass at the opposite end thereof by suction, thereby raising the level of the exposed surface of the liquid zinc at said latter end and depressing it at the former end so that the lower exposed surface is brought to a level that permits said gases and vapor to ow into said body of liquid at least 12 inches below its upper exposed surface, and retaining said vapor in said mass for sufficient time to condense substantially all of it.

4. The method of condensing zinc vapor which comprises providing a mass of molten zinc circumferentially confined except at opposite ends thereof, conducting gases and zinc vapor from a furnace to the exposed surface of said mass at one end thereof, drawing off the gases from a space above the exposed surface of said mass at the opposite end thereof by suction, thereby raising the level of the exposed surface of the liquid zinc at said latter end and depressing it at the former end so that said lower exposed surface is brought to a level that permits said gases and vapor to flow into said mass of liquid at least 12 inches b elow its upper exposed surface, conducting said gases and vapor in said mass in an inclined upward direction, and retaining said vapor in said mass for sufdcient time to condense substantially all of it.

5. The method of condensing zinc vapor which comprises providing a mass of molten zinc circumferentially confined except at opposite ends thereof, conducting gases and zinc vapor from a furnace to the exposed surface of said mass at one end thereof, drawing off the gases from a space above the exposed surface of said mass at thev opposite end thereof by suction, thereby raising the liquid zinc at said latter' end and lowering it at the former end so that the level of the upper surface of the liquid is substantially higher vertically than the level of the lower surface of the liquid and said lower surface is brought to a level that permits said gases and vapor to flow into said mass of liquid substantially below its upper surface, partially obstructing the flow of said gases and vapor in said mass thereby agitating and breaking up the same into bubbles and retarding their flow, contacting said bubbles in said mass only with the molten metal or with surfaces wiped by said metal, retaining said vapor in said mass for suiilcient time to condense substantially all of it, delivering the uncondensed gases to the space above the upper surface of said mass, and drawing off the accumulated molten metal.

6. The method of condensing zinc vapor which comprises providing a mass of molten zinc circumferentially conned except at opposite ends thereof, conducting gases and zinc vapor from a furnaceto the exposed surface of said mass at one end thereof, drawing off the gases from a space. above the exposed surface of said mass at the opposite end thereof by suction, thereby raising the liquid zinc at said latter end and lowering it at the former end so that the level of the upper surface of the liquid is substantially higher vertically than the level of the lower surface of the liquid and said lower surface is brought to a level that permits said gases and vapor to flow into said mass of liquid substantially below its upper surface, conducting said gases and vapor in said mass in an inclined upward direction, partially obstructing the flow of said gases and vapor in said mass thereby agitating and breaking up the same into bubbles and retarding their flow, contacting said bubbles in said mass only with the molten metal or with surfaces wiped by said metal, retaining said vapor in ysaid mass for sufficient time to condense substantially all of it, delivering the uncondensed gases to the space above the upper surface of said mass, regulating the temperature of said mass of liquid by cooling it, and drawing oi the accumulated molten metal.

7. Apparatus for vthe condensation of metallic` vapors such as zinc or the like comprising, in combination, a heat insulated entrance chamber connected to a source of gases and said vapors, an exit chamber, a receptacle having its respective ends connected to said chambers and normally filled with molten metal for a substantial portion of its length throughout its transverse cross-section, a suction producing device to draw off gasesz from said exit chamber and to lift the exposed upper surface of said metal substantially above its exposed lower surface, an enclosing roof portion to said receptacle in contact with and confining said molten metal intermediate said chambers, and baiiles submerged in said receptacle ,to impede and retard the flow of gases and vapors therein, whereby said vapors are condensed in said molten metal and the uncondensed gases ,are delivered to said exit chamber.

8. Apparatus for the condensation of metallic vapors such as zinc or the like comprising, in combination, a heat insulated entrance chamber connected to a source of gases and said vapors, an exit chamber, a receptacle having its respective ends connected to said chambers and normally filled with molten metal for a substantial portion of its length throughout its transverse cross-section, a suction producing device to draw off gases from said exit chamber and to lift the exposed upper surface of said metal substantially above its exposed lower surface, an inclined enclosing roof portion to said recentacle in contact with and confining said molten metal intermediate said chambers and inclined between 45 and 75 from the vertical, and bailles in said receptacle to retard the ilow of gases and vapors along said roof portion, whereby said vapors are ,condensed in said molten metal and the uncondensed gases are delivered to said exit chamber. i

9. Apparatus for the condensation of metallic vapors such as zinc or the like comprising, in combination, a heat insulated entrance chamber connected to a source of gases. and said vapors, an exit chamber, a receptacle having its respective ends connected to said chambers and normally filled with molten metal for a substantial portion of its length throughout its transverse cross-section, a suction producing device to draw off gases from said exit chamber and to lift the closing roof portion'to said receptacle in contact with and conning said molten'v metal intermediin said molten metal and the uncondensed gases are delivered to-said exit chamber.

10. Apparatus for the condensation of metallic vapors such as zinc or the like comprising, in combination, a heat insulated entrance chamber .connected Ato a source ofI gases and said vapors,

an exit chamber, a receptaclehaving its respective ends connected to said chambers and normally filled with molten metal for a substantial portion of its length throughout its transverse cross-section, a suction producing device to draw off gases from said `exit chamber and to lift the exposed upper surface of said metal substantially above its exposed lower surface, an inclined enclosing roof portion to said receptacle in contact with and confining said molten metal intermediate said chambers and at least twice as long as the vertical distance between said exposed surfaces, submerged baiiles in said receptacle to impede and retard the iiow of gases and vapors along said roof portion, whereby said vapors are condensed in said molten metal and the uncondensed gases are delivered to said exit chamber.

11. Apparatus for the condensation of metallic vapors such as zinc or the like comprising, in combination, a heat insulated entrance chamber connected to a source of gases and said vapors, an exit chamber, a receptacle having its respective ends connected to said chambers and normally filled with molten metal for a substantial portion of its length throughout its transverse crosssection, a suction producing device to draw off gases from said exit-chamber and to lift the exposed upper surface of said metal substantially above its exposed lower surface, an inclined enclosing roof portion to said receptacle in contact with and confining said molten metal intermediatek said chambers, and submerged bailies in said receptacle, to obstruct and to retard theow of gases and vapors therein, whereby said vapors are condensed in said molten metal and the uncondensed gases are delivered to said exit chamber.

12. Apparatus for the condensation of metallic vapors such as zinc or the like comprising, in combination, a heat insulated entrance chamber connected to a source of gases and said vapors, an exit chamber, a receptacle having its respective ends connected to said chambers and normally lled with molten metal for a substantial portionof its length throughout its transverse cross-section, a suction producing device to draw off gases from said exit chamber and to lift theexposed` upper surface of said metal substantially above its exposed lower surface, an inclined enclosing roof portion to said receptacle in contact with and confining said molten metal intermediate said chambers to impede and retard the flow of gases and vapors along said roof portion, whereby said vapors are condensed in said molten'metal.

13. Apparatus for the condensation of metallic vapors such as zinc or the like comprising, in combination, a heat insulated entrance chamber connected to a source of gases and said vapors, an exit chamber, a receptacle having its respective ends connected to said chambers and normally filled with molten metal fora substantial portion 75 of its length throughout its transverse cross-sectoren exposed upper surface of said metalsubstantially above its exposed. lower surface, -an inclined .en-

tion, a suction producing device to draw off gases from said exit chamber' and to lift the exposed upper surface of said metalsubstantially above its exposed lower surface, an enclosing roof portion to said receptacle inclined between 45 and 75 from the vertical and4 in contact with and confin# ing said molten metal intermediate said chambers to impede and retard the flow of gases and vapors along said roof portion, whereby said vapors are condensed in said molten metal.

14. Apparatus for the condensation of metallic vapors such as zinc or the like comprising, in combination, a heat insulated entrance chamber, connected to a source of gases and said vapors, an exit chamber, a receptacle having its respective ends connected to said chambers and normally filled with molten metal for a substantial portion of its length throughout its transverse cross-section, a suction producing device to draw off gases from said exit chamber and to lift the exposed upper surface of said metal substantially above its exposed lower surface, said receptacle having an enclosing roof portion in contact with and confining vsaid molten metal intermediate ends connected to said chambers and normally filled with molten metal for a substantial portion of its length throughout its transverse cross-section, said receptacle having an inclined enclosing roof portion in contact with and confining said molten metal intermediate said chambers, a suction producing device to draw o gases from said exit chamber and to lift the exposed upper sur'- face of said metal and depress its exposed lower surface below the lower end of said roof portion, and submerged transverse baffles in said receptacle spaced from the roof portion thereof to prevent surging of the molten metal.A

16. Apparatus for the condensation of metallic vapors such as zinc or the like comprising, in combination, a heat insulated entrance chamber connected to a source of gases and said vapors, an exit chamber, a receptacle having its respective ends connected to said chambers and normally lled with molten metal for a substantial portion of its length throughout its transverse crosssection, said receptacle having an inclined enclosing ro'of portion in contact with and confining said molten metal intermediate said chambers, and a. suction producing device to draw off gases from said exit chamber and to create. and maintain the exposed lower surface of said molten metal below the lower end of said roof portion, whereby said vapors are introduced into said molten metal immediately above the lower exposed surface thereof.

17. Apparatus for the condensation of metallic vapors such as zinc or the like comprising, in combination, a heat insulated entrance chamber connected to a source of gases and said vapors, an exit chamber, a receptacle having its respective ends connected to said chambers and normally lled with molten metal for a substantial portion of itslength throughoutits transverse cross-section, said receptacle having an .inclined enclosing roof portion in contact with and confining said molten metal intermediate said cham? bers and a suction producing device to draw oiI gases from said exit chamber and to create and maintain theexposed lower surface of said molten metal below the lower end of said roof portion, whereby said vapors are introduced into said molten metal immediately above the lower exposed surface thereof, and batlles in said receptacle to impede and retard the flow of the 0 vapors therein.

18. A method of condensing zinc vapors which comprises passing the zinc vapors into a body 'of zinc in liquid form and retardlng the passage of vapors through the liquid zinc so that substantially all of the zinc is condensed in contact only with the liquid zinc and with surfaces actively wiped by the liquid zinc. 

